With the advent of widespread use of cellular telephones and the corresponding growth of wireless subscribers for using such telephones, a need has arisen for providing services and modifying programmed information within each of the devices used by wireless subscribers. Before describing how this need has been addressed, however, a general structure of a wireless communications systems will be described. The infrastructure of a wireless communications network generally includes multiple mobile switching centers (MSCs) which provide wireless services, control, and tracking of mobile stations within a predetermined area.
The term "mobile station" (MS) as used in the remainder of this specification and the claims is intended to refer to any wireless communication device whether the device is mobile or fixed and whether used for the transmission of voice, data or facsimiles. Subscriber Unit is another term that is used in the art to describe such a device.
A home location register (HLR) is typically utilized in the infrastructure for a wireless communications network. For each MS it serves, the HLR retains a profile of information about the mobile station, including special features for which the mobile station is authorized and where the MS is currently located. A mobile station registers its location, in terms of a currently serving MSC, on its home HLR. An MSC that is currently serving a mobile station will retrieve the MS's profile from the HLR, and store the profile in a visiting location register (VLR) that is often co-located with the serving MSC.
Subsequently, when a call for a mobile station is received by a home network, the home HLR determines where to route the call. Through this method, the home network is able to transfer the call to the current visited MSC so that the mobile station receives the call even when it is not within its own home network.
In some wireless communication networks, a number assignment module (NAM) is implemented in each of the mobile stations. The NAM provides a memory for the mobile station to hold certain relevant information. That information may include a roaming list of available roaming systems, as well as certain operational parameters such as the mobile station's directory number. It should be noted that the parameters maintained in a mobile station's NAM are assigned by a service provider to control wireless network usage. Equivalent parameters in a wireline telephone network are completely under the control of the service provider and are not stored in equipment belonging to the subscriber. However, because wireless technology breaks the direct link between a mobile station and the communication network, some operational parameters must be stored in the mobile station. As a result, wireless service providers have historically accepted a loss of control over NAM parameters once initial programming is complete.
Typically, the NAM is programmed when a mobile station is first activated. For example, before a mobile station is first utilized, the NAM is programmed by the service provider to have a preselected roaming list, services, and a directory number to be associated with the mobile station itself.
When any of the network-stored parameters that were used to supply data originally programmed into the NAM are modified, those modifications must be reflected by modifying the NAM so that the mobile station may operate correctly. In such a situation, the subscribers are typically required to physically take the mobile station to a location specified by the service provider for NAM reprogramming. Alternatively, an Over-The-Air Service Provisioning (OTASP) mechanism may be used to either activate a new mobile station, modify the existing services provided to a subscriber, or update the existing operation parameters without the intervention of a third party. OTASP is defined in a telecommunication industry association (TIA) standards having designations of IS-683 and IS-725. However, the OTASP mechanism, as specified in IS-683 and IS-725, is initiated only by the subscriber. Furthermore, the OTASP mechanism may require connection to a customer service center of a service provider for interaction with a customer service representative. Thus, while OTASP sessions do not require the mobile subscriber to physically take their mobile stations to a location specified by the service provider, subscriber effort is still required to accomplish the updating process.
Additionally, with the use of the OTASP mechanism, security may become an issue. Specifically, a wireless service provider should be able to insure that the NAM is not programmed from a renegade source. In the OTASP mechanism, a service program lock (SPL) procedure is utilized. In the SPL procedure, a password is sent to the mobile station and then used to "unlock" the mobile station if the password corresponds to that stored in the mobile station. If the password does not correspond to that stored in the mobile station, the message and programming effort is rejected. However, a lock procedure, such as SPL, where a given password is transmitted over the air, is subject to unauthorized interception. Thus any over-the-air transmitted passwords or unlocking signatures may need to be altered with each transmission to lower the risk of improper usage of such passwords by unauthorized entities.
Therefore, in addition to the need to easily program a mobile station within a wireless communication network, there exists a need to insure that such programming is performed in a secure manner such that a subscriber's mobile station is not "hijacked" for unauthorized purposes. Furthermore, a need exists for a programming methodology that may be easily implemented with minimal interruption and inconvenience to the wireless subscriber.